68300

If you don't generate an AVEC signal from some source, the &*%$$^&&$#^&@ thing ain't going to work.

Charlie

-----Original Message-----
From: Andrei Chichak [mailto:acpmiedm@...]
Sent: Wednesday, July 16, 2003 10:50 AM
To: 68300@yahoogroups.com
Subject: RE: [68300] IRQ7 acting odd


Good morning Scott, Sheldon, Brian, Charlie, and everybody else,

I think that I am missing something here, and I think it has a lot to do 
with AVEC and DSACK.

What I am trying to do is have the external RTC clock yank down on IRQ7* 
and trigger the execution of some code on the '332. The RTC looks like 128K 
of static RAM and is mapped onto locations 0x600000 to 0x61FFFF controlled 
by CS5, thus;

         MOVE.W  #$6005,$FFFA60  ; CSRBR5 128k area reserved at $600000 for 
NVRAM and clock
         MOVE.W  #$5830,$FFFA62  ; CSOR5

I will not be providing an autovector vector on the data bus, just relying 
on IRQ7* vectoring through location VBR+0x7c. So I do not turn on the AVEC 
bit in CSOR5 or any other CSOR register.

Within the interrupt routine, I clear the source of the interrupt returning 
IRQ7* to the high state then do the RTE. This should avoid the level 
sensitivity reasserting the interrupt.

Is the processor expecting the vector to be supplied on the data bus at 
interrupt time? Can't I just use the exception vector table with a simple, 
low going, input pulse? Does DSACK have to be externally generated? And 
what about Naomi? (sorry I just had to throw that in).

Thanks,
Andrei

At 07:15 AM 7/16/2003 -0700, you wrote:
>Andret,
>
>The CPU32 is very good about giving stack information.  When the machine 
>takes a double bus fault, there will be a lot of information put on the 
>stack.  If you will get that data and send it to me, I will try to help 
>you decipher it.
>
>The most likely cause for a double bus fault is that there is nothing to 
>"DSACK" the level 7 interrupt service routine.  However, the information 
>put on the stack will help determine what is going on.
>
>What you might have to do is write a short routine to dump the information 
>on the stack.  If the machine simply halts, you can take the debugger and 
>manually enable the stack memory and then read the stack memory through 
>the debugger.
>
>If none of this makes sense, send me an email and I will give more details.
>
>Charlie

-------
Andrei Chichak               #200 10835-120 Street
Senior Software Developer    Edmonton, Alberta
Pulmonox Medical Inc.        Canada
                              T5H 3P9
                              (W) (780) 451-3660
                              (F) (780) 452-0169

Lat: 53° 33' 13.548" N
Lon: 113° 31' 43.164" W



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